(1) Field of the Invention
This invention relates to the stabilisation of a rock formation. More particularly the invention relates to a method of stabilising a rock formation and to apparatus for use in such method. The invention finds particular application in the stabilization of rock formations underground in mine excavations, where cracks or fissures in the rock formations can cause danger of dislodged rock segments.
(2) Description of the Prior Art
U.S. Pat. No. 2,667,037--Thomas et al, Jan. 26, 1954, discloses anchor bolts protected by grout which holds the bolts firmly in the rock strata and seals the bolts from atmosphere and hence inhibits corrosion and weakening of the bolts.
U.S. Pat. No. 3,222,873--Williams, Dec. 14, 1965, discloses the pumping of cementitious grout under pressure into the clearance space between an anchor bolt and the wall of the borehole. The patent is directed to a more efficient method of grouting.
Later patents, also in the name of Williams, are directed to different aspects of grouting anchor bolts in holes in rock formations. The Patents are:
U.S. Pat. No. 3,234,742 Feb. 15, 1966 PA1 U.S. Pat. No. 3,326,004 June 20, 1967 PA1 U.S. Pat. No. 3,379,016 Apr. 23, 1978 PA1 U.S. Pat. No. 3,415,066 Dec. 10, 1978.
U.S. Pat. No. 3,618,326--Nov. 9, 1971, in the name of Montgomery, reviews certain prior art directed to the use of resins instead of grout with anchor bolts in holes. The Montgomery patent itself is directed to a particular way in which the resin components are packed in a single package but with two compartments. In the Montgomery patent and in the prior art relevant to anchor bolts reviewed therein, it appears that resins are used as a substitute for grout, and that the resins perform no function other than to protect the bolts from corrosion and/or to locate the expansion shells of the bolts in position.